Paul Erdős1913–1996- My Brain Is Open: The Mathematical Journeys of Paul Erdos (1998) by Bruce Schechter, p. 99
- Common remark when breaking off work for the night, as quoted in “The Magician of Budapest” in The Edge of the Universe: Celebrating Ten Years of Math Horizons (2007) by Deanna Haunsperger and Stephen Kennedy, p. 111
- Frequent remark, as quoted in My Brain Is Open: The Mathematical Journeys of Paul Erdos (1998) by Bruce Schechter, p. 14





